The effect of nedocromil sodium and cromolyn sodium on antigen-induced responses in allergic sheep in vivo and in vitro.

We studied the effects of nedocromil sodium and cromolyn sodium on early and late bronchial responses to inhaled Ascaris suum antigen in allergic sheep in vivo, and the antigen-induced contractile responses of sheep tracheal smooth muscle in vitro. For the in vivo studies the sheep were pretreated with aerosols of placebo (buffered saline solution), 20 mg of nedocromil sodium, or 20 mg of cromolyn sodium (both dissolved in 3 ml of buffered saline solution) and then challenged with aerosol antigen. Specific pulmonary resistance (SRL) was measured before and after challenge to document the responses of the airways. In the trial with placebo, challenge with antigen resulted in significant early and late increases in SRL. Treatment with nedocromil sodium significantly reduced the early response to antigen and blocked the late response. Cromolyn sodium gave the same results; there were no statistical differences between the responses of the airways for the two dogs. In vitro nedocromil sodium at doses of 10(-6)M and 10(-5)M inhibited significantly the contractile responses of sheep tracheal smooth muscle to A suum. Cromolyn sodium only showed efficacy at 10(-5)M. These results suggest that nedocromil sodium may be potentially useful in the treatment of reversible allergic disease of the airways.